JP2980973B2 - Siamese type cylinder block mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold for molding a Siamese type cylinder block, and more specifically, it can improve the quality and strength of a Siamese type cylinder block, and The present invention relates to a Siamese type cylinder block molding die having a longer life than a conventional die.

2. Description of the Related Art It is customary to manufacture a complicated shape such as a cylinder block of an internal combustion engine by casting.
That is, the molten metal is introduced into the cavity of the mold to form the molten metal, and then the molded molten metal is cooled and solidified to obtain a cast product. For example, when a plurality of cylinders are to be manufactured by casting a cylinder block of a siamese-type cylinder that shares one water jacket, in order to form a water jacket that surrounds the cylinder barrel of the plurality of cylinders, The mold for forming the water jacket portion is arranged so as to surround and flex the portion where the cylinder barrel is formed. After the molten metal is introduced into the cavity of the mold for forming the water jacket portion, the molten metal is cooled and solidified, whereby a void portion serving as a water jacket portion is formed and a partition wall is formed between the cylinder barrels. .

Normally, a Siamese type cylinder block has a thick part and a thin part. In other words, a thick portion and a thin portion are formed by cooling and solidifying the molten metal. However, at the time of this cooling and solidification, the solidification rate of the molten metal at the portion to be thickened is significantly different from that of the molten metal at the portion to be thinned. In other words, the time required for the molten metal in the thick portion to completely solidify is
This is longer than the time required for the molten metal in the thin portion to completely solidify. For example, the solidification rate of the molten metal at the portion serving as the journal receiving portion of the crankshaft and the solidification speed of the molten metal at the portion serving as the partition wall (upper surface of the journal receiving portion) between the cylinder barrels are different from those of the portion serving as the main body of the Siamese type cylinder block. It is significantly slower than the solidification rate of the molten metal.

When the molten metal is solidified, the molten metal is slightly shrunk. When the solidification rate of the molten metal is different between the thick part and the thin part, the shrinkage time of the molten metal in the thick part and the molten metal in the thin part are increased. Does not coincide with the shrinkage time of the melt, so that the shrinkage becomes uneven as a whole of the molten metal. This phenomenon is particularly remarkable when the entire molten metal is forcibly cooled and solidified in a short time. In this case, a so-called shrinkage occurs in the central portion of the thick portion, and as a result, a burrow or a crack may occur. Moreover,
The Siamese type cylinder block may be deformed by the internal stress generated by the shrinkage.

For this reason, when obtaining a Siamese type cylinder block as a cast product, the solidification speed of the molten metal is reduced, and the molten metal is solidified for a long time.

[Problems to be Solved by the Invention] However, as described above, if it takes a long time to cool and solidify the molten metal, there is a problem that the production efficiency of the cylinder block cannot be improved.

As a method of avoiding such a problem, when cooling and solidifying the molten metal, it is conceivable to locally cool only the molten metal at a portion to be a thick portion. However, when such local cooling is performed, heat conduction of the mold and heat of the molten metal itself occur, so that the thin-walled portion of the die and the molten metal of the thin-walled portion are cooled more than necessary. As a result, the entire molten metal is not solidified at a uniform solidification rate.

On the other hand, as a method of preventing shrinkage cavities and cracks in the Siamese type cylinder block without causing shrinkage in the journal receiving portion even if the solidification speed of the melt is increased, casting by mixing carbon fiber etc. in the melt is performed. Conceivable. However, this method has a disadvantage that the price of the Siamese type cylinder block rises.

Further, during the above-described casting, thermal stress is generated in the water jacket portion forming mold. Furthermore, during the casting, there is a problem that the molten metal is burned into the water jacket forming die. For this reason, the mechanical strength of the water jacket molding die gradually decreases as the number of castings increases. That is, in the water jacket molding die according to the related art, since the life is short, there is an inconvenience that the same replacement mold must be kept at all times.

The present invention has been made in order to solve the various problems described above, and when obtaining a Siamese type cylinder block by casting, a molten metal such as a portion that becomes a thick portion, for example, a portion that becomes a journal receiving portion of a crankshaft. And other parts, for example, the molten metal of the part to be the body part of the cylinder block can be simultaneously solidified, whereby a high-quality and high-strength Siamese-type cylinder block without shrinkage cavities and cracks is obtained. A long-life siamese-type cylinder block molding die capable of relieving thermal stress generated in a water jacket molding die and avoiding seizure of molten metal on the water jacket molding die. The purpose is to:

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides a siamese-type cylinder block molding die, a first die and a second die for molding a cylinder block. And a water jacket molding die disposed in a casting section defined by the first mold and the second mold, wherein the water jacket molding die is a Siamese type cylinder block. And a pair of holes facing each other facing the position where the journal receiving portion of the crankshaft is formed, and a pair of cooling pipes inserted into the pair of holes.

[Operation] In the above configuration, in particular, in the present invention, by providing a cooling means in the water jacket molding die, the molten metal at the portion to be the journal receiving portion of the crankshaft, which is a thick portion, and the Siamese type cylinder It is possible to solidify the melt at the same solidification rate as that of the molten metal such as the portion that becomes the main body of the block. Therefore, the occurrence of the closing of the portion serving as the journal receiving portion is suppressed. Also, since the water jacket molding die itself is cooled, the thermal stress generated in the water jacket molding die during casting is remarkably reduced, and the molten metal in the water jacket molding die is reduced. Burning is avoided. As a result, the life of the water jacket molding die is prolonged.

EXAMPLES Preferred examples of the Siamese type cylinder block molding die according to the present invention will be described below in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 designates a siamese-type cylinder block molding die having a water jacket molding die 20 according to the present embodiment. The siamese-type cylinder block molding die 10 is a water jacket molding die.
In addition to 20, a first mold 12, a second mold 14, a third mold 16, a bore core mold 18, and a journal receiving part forming mold.
15 and a stud hole casting pin 26. The first mold 12 and the second mold 14 are formed with a runner 24 for guiding the molten metal to a casting portion 34 which is a cavity.

As shown in FIG. 2, holes 28, 28 are formed in opposed thick portions 20a, 20a of the water jacket portion forming mold 20, respectively.
Are formed. And, in these holes 28, 28, respectively, a journal receiving portion, an upper surface of the journal receiving portion,
That is, cooling means 22, 22 for cooling the molten metal at a portion serving as a partition wall between the cylinder barrels are inserted. Hole
The pipes 22a, 22a inserted into the pipes 28, 28 face each other.

As shown in FIG. 1, each cooling means 22 is composed of a pipe 22a inserted to the tip of the hole 28, and a refrigerant (not shown) flowing through the pipe 22a. This pipe 22a is connected to a not-shown refrigerant circulation means,
The refrigerant can be circulated and circulated in the pipe 22a by the refrigerant circulating means. Water can be used as the refrigerant. Further, depending on the composition of the molten metal, liquid nitrogen, ammonia gas, or the like can be used.

The cylinder sleeve 30 shown in FIG. 2 is fitted to the bore support pin portion 18a of the bore core 18, as shown in FIG. That is, it is integrated with the cylinder body by casting, and forms the inner wall of the cylinder barrel.

A high hardness cast iron is exemplified as a constituent material of the cylinder sleeve 30. As described above, by forming the inner wall of the cylinder barrel with the cylinder sleeve 30 made of high-hardness cast iron, wear of the cylinder barrel due to sliding of the piston is suppressed, and as a result, the life of the cylinder block can be extended.

FIG. 3 shows a plan view of the siamese-type cylinder block molding die 10 excluding the third die 16. FIG. 1 is an explanatory longitudinal sectional view taken along the line AA 'shown in FIG.

As shown in FIG. 1, a first mold 12, a second mold
14. The casting portion 34 defined by the third mold 16 forms the first casting portion 34a for forming a partition wall between the cylinder barrels of the Siamese type cylinder block and the outer wall of the Siamese type cylinder block. Second casting 34 for
b, a third casting 34c for forming a journal receiving portion of the crankshaft, and first and second castings 34a,
It comprises a thick cast portion 32 between 34b and a third cast portion 34c. The stud hole casting pin 26 is inserted into the second casting portion 34b.

The siamese-type cylinder block molding die 10 according to the present embodiment is basically configured as described above. Next, the operation and effects thereof will be described.

First, the journal receiving portion forming die 15 is placed on the second die 14, and the bore core 18 is attached to the crankshaft receiving portion forming die 15.

Next, as shown in FIGS. 1 and 2, the cylinder sleeve 30 is fitted to the bore support pin portions 18a of the respective bore cores 18.

Next, the first mold 12 is attached to a predetermined position.
Third mold 16 with mold 20 for forming water jacket part
And the second mold 14 is engaged with the
Define 34.

Next, the molten metal is supplied from the runner 24 to the casting section 34. At this time, the supply of the molten metal is performed, for example, by connecting a pressurizing means (not shown) to the passage of the molten metal and pressurizing the molten metal by the pressurizing means. In this case, by continuing to pressurize at a predetermined pressure even after supplying a predetermined amount of molten metal, the molten metal can be stored at a predetermined position of the casting unit 34 until the casting is completed. Further, by adjusting the pressure to be applied, the molten metal can be uniformly supplied to the end of the cast portion 34 where the molten metal does not easily enter.

As the molten metal, for example, a molten metal of an alloy mainly composed of aluminum is used. By using such a molten metal, the weight of the Siamese type cylinder block can be reduced.

Next, a coolant such as water is circulated by a coolant circulating means (not shown) in the pipe 22a provided in the water jacket portion forming mold 20. Due to the cooling action of the refrigerant, the solidification rate of the molten metal at the portion of the crankshaft, which is the thick portion, which will be the journal receiving portion, and the molten metal at the portion of the upper portion of the journal receiving portion, which will be the partition wall between the cylinder barrels, are increased. Therefore, the solidification rate of the molten metal which becomes another part is substantially equal to the solidification rate. Therefore, the occurrence of shrinkage during casting is avoided. As a result, generation of cracks and shrinkage cavities is avoided, and a high-quality Siamese-type cylinder block can be obtained. Further, in such a Siamese type cylinder block, gas pressure leakage does not occur.

This is because the structure photograph of the thick part of the Siamese type cylinder block taken with an optical microscope (magnification: 100
4a and 4b. That is, FIG. 4A shows the use of the Siamese type cylinder block molding die 10 according to the present embodiment including the water jacket portion molding die 20, and the water jacket portion molding die 20 is cooled by the cooling means 22. It is a metal structure of a thick portion of a Siamese type cylinder block obtained by casting a molten metal while cooling. On the other hand, FIG. 4b shows a metal structure of a thick portion of a siamese-type cylinder block cast using a siamese-type cylinder block molding die according to the prior art. No cracks are observed in the metal structure of FIG. 4A, but cracks are clearly observed in the metal structure of FIG. 4B.

Further, each particle in the metal structure of FIG. 4A is finer than each particle in the metal structure of FIG. 4B. From this, it is understood that the Siamese type cylinder block having the metal structure shown in FIG. 4A has higher strength than the Siamese type cylinder block having the metal structure shown in FIG. 4B.

Further, by circulating and circulating the refrigerant in the pipe 22a as described above, the water jacket molding die is formed.
The seizure of the molten metal to the casting 20 can be suppressed, and the initial temperature (initial) of the casting section 34 can be set low, so that the temperature amplitude becomes small. Applying excessive thermal stress to the mold 20 can be avoided. Therefore, the life of the water jacket portion forming mold 20 is extended. That is, since the inconvenience of always keeping the same replacement mold is eliminated, a reduction in production cost can be achieved.

[Effects of the Invention] As described above, according to the siamese-type cylinder block molding die according to the present invention, in particular, the temperature of the water jacket portion molding die is configured to be controlled. The solidification rate of the molten metal at the portion serving as the receiving portion and the molten metal at the portion serving as the partition wall between the cylinder barrels is substantially equal to the solidification speed of the molten metal at the other portions.
Thereby, during casting, the occurrence of shrinkage is significantly suppressed,
A high quality Siamese type cylinder block free from shrinkage cavities and cracks can be obtained.

Further, since the metal structure is refined, the strength of the Siamese type cylinder block is improved. Furthermore, in the Siamese type cylinder block molding die, the seizure of the molten metal on the water jacket portion molding die can be suppressed, and the initial temperature of the cast portion can be set low. Thereby, the durability of the mold for forming the water jacket portion is improved, and the life is prolonged. As a result, there is an effect that a reduction in manufacturing cost is achieved.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view taken along the line AA ′ of FIG. 3 of a siamese-type cylinder block molding die according to the present embodiment. FIG. 2 is a siamese-type cylinder block molding die according to the present embodiment. FIG. 3 is a schematic partial plan view of a siamese-type cylinder block forming mold according to the present embodiment, and FIG. 4a is a schematic partial plan view of a siamese-type cylinder block forming mold according to the present embodiment. 4B is a photograph showing a metal structure near the journal receiving portion cast using the siamese-type cylinder block molding die. FIG. 4b is a diagram illustrating a metal structure cast using the siamese-type cylinder block molding die according to the related art. 4 is a photograph showing a metal structure near a journal receiving portion. 10: Siamese type cylinder block forming die 12: First die 14: Second die 15: Journal receiving part forming die 16: Third die 18: Bore core 20 ... Mold for forming the water jacket part 22 ... Cooling means 22a ... Cooling pipe 24 ... Runner 26 ... Casting pin for hole for stud 30 ... Cylinder sleeve

Continuation of the front page (72) Inventor Jun Ohashi 1-10-1 Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (72) Inventor Kenji Miyamoto 1-1-1 Shin-Sayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (56) References Hikaru No. 2-138056 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B22C 9/06, 9/24

Claims (1)

(57) [Claims] 1. A siamese-type cylinder block molding die, comprising: a first die and a second die for molding a cylinder block; and the first and second dies. A water jacket portion forming mold disposed in the casting portion to be formed, wherein the water jacket portion forming mold faces each other, facing the position where the journal receiving portion of the crankshaft of the Siamese type cylinder block is formed. And a pair of cooling pipes inserted into said pair of holes.